Thomas Nagel (born 1937) is an American philosopher, currently University Professor and Professor of Philosophy and Law at New York University. His main areas of philosophical interest are philosophy of mind, political philosophy, ethics. He is widely known for his critique of reductionist accounts of the mind in his essay "What Is it Like to Be a Bat?" (1974). However, he is also well known for his contributions to ethical, political, and social issues. For example, in The Possibility of Altruism (1970), Nagel defends altruism—the view that people can commit acts that benefit another without the expectation of benefit for oneself—against rival views, such as egoism.

Much of Nagel's work concerns the tension between objective and subjective perspectives: on reasons for action, on agency, on experience, and on reality as a whole. He is known within the field of philosophy of mind as an advocate of the idea that consciousness and subjective experience cannot be reduced to brain activity. Along with Bernard Williams, he has also contributed much to the early development of the problem of moral luck, detailing its various aspects, and analyzing its impact on ethics and moral evaluation. For many years, Nagel has conducted a seminar noted for an array of guest speakers with his colleague Ronald Dworkin.

In "What is it Like to Be a Bat?", Nagel argues that consciousness has essential to it a subjective character, a what it is like aspect. He states that "an organism has conscious mental states if and only if there is something that it is to be that organism—something it is like for the organism."[3] Nagel also suggests that the subjective aspect of the mind may not ever be sufficiently accounted for by the objective methods of reductionistic science. He claims that "[i]f we acknowledge that a physical theory of mind must account for the subjective character of experience, we must admit that no presently available conception gives us a clue how this could be done."[4] Furthermore, he states that "it seems unlikely that any physical theory of mind can be contemplated until more thought has been given to the general problem of subjective and objective."[5]

While Nagel is sometimes categorized as a dualist for these sorts of remarks, he is more precisely categorized as an anti-reductionist. Nagel (1998) writes:

“

...I believe that there is a necessary connection in both directions between the physical and the mental, but that it cannot be discovered a priori. Opinion is strongly divided on the credibility of some kind of functionalist reductionism, and I won't go through my reasons for being on the antireductionist side of that debate. Despite significant attempts by a number of philosophers to describe the functional manifestations of conscious mental states, I continue to believe that no purely functionalist characterization of a system entails—simply in virtue of our mental concepts—that the system is conscious.[6]